A solar cell module includes a plurality of solar cells. In recent years, through-hole type solar cells have been considered as one of the measures to increase the efficiency of a solar cell module.
A through-hole type solar cell is provided with through holes that pass through from the light receiving surface side of the solar cell to the back surface side so as to eliminate electrodes on the light receiving surface side or reduce the number of electrodes on the light receiving surface side as compared to the case of a conventional solar cell, thereby increasing the light receiving surface area and achieving a higher efficiency. For instance, a configuration has been disclosed, in which the electrode on the light receiving surface side is disposed on the surface of the crystal substrate of a first conductivity type, then a compound semiconductor layer of the same first conductivity type and another compound semiconductor layer of a second conductivity type different from the first conductivity type are deposited thereon in order, and the electrode on the light receiving surface side and the electrode on the back surface side are brought into conduction via through holes that penetrate the crystal substrate and the compound semiconductor layers (see, for example, Japanese Patent Application Laid-open No. 63-211773 (Patent Document 1)).
Also, a solar cell in which the range of formation of the second conductivity type layer having an opposite conductivity type to that of the semiconductor substrate of one conductivity type is extended to the periphery of the back surface side of the through holes has been disclosed (see, for example, Japanese Patent Publication No. 2002-500825 (Patent Document 2)).
With either of the above-described conventional techniques, the materials for forming electrodes or through holes contain glass in order to improve the bond strength with the semiconductor substrate. However, the problem is that the presence of such glass can cause the output characteristics of a solar cell to deteriorate.